How to avoid duplicate page content

[bruki]

I have over 5.000 duplicate page content because my urls contains ?district=1&sort=&how=ASC¤cy=EUR. How can I fix this?

[NakulGoyal]

There are multiple ways of solving this. However, the best solution is to implement rel=canonical tag in your pages.

You could technically do a robots.txt exclusion for such pages, but that's not recommended. Just use one primary URL. So for example your URL is http://www.example.com/red-widgets.php and you have sorting options for that URL, the template/header code should contain:

on all the sort URLs. This acts as a very strong directive to Google and acts as a 301 from all such URLs to your main URL for that product/category.

[SEOKeith]

Personally long term I would work on changing the URL's so they are human readable but for now to "fix" the issue I would advise you use rel=canonical here is a guide... http://www.seomoz.org/blog/complete-guide-to-rel-canonical-how-to-and-why-not